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Topic Review
Intermetallic Quasicrystals
A quasicrystal is the natural extension of the notion of a crystal to structures with quasiperiodic, rather than periodic, translational order. Intermetallic quasicrystals are a class of quasiperiodically ordered solids made of typical metallic atoms, though they do not exhibit the physical properties that usually signal the presence of metallic bonding, and their electrical and thermal transport properties resemble a more semiconductor-like than metallic character. The distribution of atoms throughout the space in these compounds exhibits a characteristic self-similar, scale invariant symmetry, based on a hierarchy of nested atomic clusters.
  • 505
  • 10 Jan 2022
Topic Review
International Course-based Undergraduate Research Experiences
Course-based Undergraduate Research Experiences (CUREs) are a proven methodology for transforming short-term study abroad to yield higher impact and quality student outcomes, especially as they relate to teaching environmental sustainability.
  • 648
  • 30 Dec 2020
Topic Review
International Space Station Maintenance
Since construction started, the International Space Station (ISS) programme has had to deal with several maintenance issues, unexpected problems and failures. These incidents have affected the assembly timeline, led to periods of reduced capabilities of the station and in some cases could have forced the crew to abandon the space station for safety reasons, had these problems not been resolved.
  • 563
  • 02 Nov 2022
Topic Review
International Space Station Program
The International Space Station program is tied together by a complex set of legal, political and financial agreements between the fifteen nations involved in the project, governing ownership of the various components, rights to crewing and utilization, and responsibilities for crew rotation and resupply of the International Space Station. These agreements tie together the five space agencies and their respective International Space Station programs and govern how they interact with each other on a daily basis to maintain station operations, from traffic control of spacecraft to and from the station, to utilization of space and crew time. In March 2010, the International Space Station Program Managers from each of the five partner agencies were presented with Aviation Week's Laureate Award in the Space category, and NASA's International Space Station Program was awarded the 2009 Collier Trophy.
  • 566
  • 10 Nov 2022
Topic Review
Interpenetrating Bulk Heterojunction Quantum Dot Solar Cells
Interpenetrating bulk heterojunction (IBHJ) quantum dot solar cells (QDSCs) offer a direct pathway for electrical contacts to overcome the trade-off between light absorption and carrier extraction. However, their complex three-dimensional structure creates higher requirements for the optimization of their design due to their more difficult interface defect states control, more complex light capture mechanism, and more advanced QD deposition technology. ZnO nanowire (NW) has been widely used as the electron transport layer (ETL) for this structure. Hence, the optimization of the ZnO NW morphology (such as density, length, and surface defects) is the key to improving the photoelectric performance of these SCs.
  • 419
  • 18 Feb 2022
Topic Review
Intraretinal Fluid Pattern Characterization
The accumulation of fluids in the retinal layers is one of the main causes of blindness in developed countries. The main strategy for its study and diagnosis is through the use of Optical Coherence Tomography (OCT) images. This allows experts to observe the layers of the retina in a cross-sectional view. Commonly, for the analysis of these accumulations by means of computer diagnostic support systems, precise segmentation strategies are employed.
  • 2.7K
  • 22 Apr 2021
Topic Review
Introduction to the Mathematics of General Relativity
The mathematics of general relativity is complex. In Newton's theories of motion, an object's length and the rate at which time passes remain constant while the object accelerates, meaning that many problems in Newtonian mechanics may be solved by algebra alone. In relativity, however, an object's length and the rate at which time passes both change appreciably as the object's speed approaches the speed of light, meaning that more variables and more complicated mathematics are required to calculate the object's motion. As a result, relativity requires the use of concepts such as vectors, tensors, pseudotensors and curvilinear coordinates. For an introduction based on the example of particles following circular orbits about a large mass, nonrelativistic and relativistic treatments are given in, respectively, Newtonian motivations for general relativity and Theoretical motivation for general relativity.
  • 784
  • 01 Dec 2022
Topic Review
Ion Channel and Bioinformatics
Ion channels are linked to important cellular processes. The use of artificial intelligence (AI) in bioinformatics and computational molecular biology research has been growing fast over the last two decades. Bioinformatics methods attempt to model known biological structures and predict unknown ones. Versatile bioinformatics techniques are capable of storing the information processed in various biological and biophysical studies in the created databank, and calling and utilizing the information from the databank in pinpointing crucial molecular processes of an individual system or collective ones. The techniques thus help establish scientific links between various mechanisms and processes and produce concluding evidence that is otherwise often unattainable using conventional theoretical and experimental techniques. Besides, computational techniques are popularly found to model the biomolecular complexes in silico studies to mainly address their statics, dynamics, and energetics in an artificially constructed, yet mimicking the biological systems’ environment.
  • 570
  • 08 Oct 2021
Topic Review
Ion-Exchange
According to Encyclopedia Britannica, ion-exchange process can be defined as “any class of chemical reactions between two substances (each consisting of positively and negatively charged species called ions) that involves an exchange of one or more ionic components”. This is the case, for example, of a multi-component oxide glass immersed – at a given temperature – in a mixture of molten salts containing metal ions (typically nitrates such as silver nitrate AgNO3, potassium nitrate KNO3, copper nitrate Cu(NO3)2, sodium nitrate NaNO3, etc.). Because of the high temperature at which the process occurs and concentration gradient established in proximity of the interface between glass and molten salt, sodium ions Na+ present within the compound glass migrate in the solution and are replaced by cations originally contained in the salt melt (e.g., Ag+, K+, Cu2+, etc.). Due to the different size and polarizability of the ions participating in the process, the glass modifies its network locally in the exchanged regions, with particular reference to its density and, therefore, to its refractive index. This paves the way for the production of graded-index optical components and waveguides, for passive and active integrated optical devices. Furthermore, the K+ – Na+ exchange is the basis for the chemical strengthening of the glass, which allows to obtain mechanically resistant glasses in increasingly thinner thicknesses for applications in smartphone technology and flexible photonics. Finally, the possibility of inducing the formation of noble metal nanoparticles in an ion-exchanged glass following particular thermal post-process techniques allows the realization of new low-cost optical platforms for sensing and photovoltaic applications.
  • 853
  • 31 May 2021
Topic Review
Ion-Mobility Spectrometry
Ion mobility spectrometry (IMS) is an analytical technique used to separate and identify ionized molecules in the gas phase based on their mobility in a carrier buffer gas. Though heavily employed for military or security purposes, such as detecting drugs and explosives, the technique also has many laboratory analytical applications, including the analysis of both small and large biomolecules. IMS instruments are extremely sensitive stand-alone devices, but are often coupled with mass spectrometry, gas chromatography or high-performance liquid chromatography in order to achieve a multi-dimensional separation. They come in various sizes, ranging from a few millimeters to several meters depending on the specific application, and are capable of operating under a broad range of conditions. IMS instruments such as microscale high-field asymmetric-waveform ion-mobility spectrometry can be palm-portable for use in a range of applications including volatile organic compound (VOC) monitoring, biological sample analysis, medical diagnosis and food quality monitoring. Systems operated at higher pressure (i.e. atmospheric conditions, 1 atm or 1013 hPa) are often accompanied by elevated temperature (above 100 °C), while lower pressure systems (1-20 hPa) do not require heating.
  • 490
  • 30 Nov 2022
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